They both have a 276 but M20 is a flange mount, 16H is a spigot mount. Which bike are you looking for. I/we can give you the full spec if you need it. Ron
The number for the 16H is 276AE/1BE....The M20 is 276C/1B. But any 1" 276 with the correct body type can be configured to suit with the correct slide/jets etc. Ron